140 STKATIGKAPIIICAL GEOLOGY. 



to the west, the succeeding ledges of Bald mountain being very porphy- 

 ritic. 



Although the positions are often obscure, it appears plain that, from 

 the passage of the Eagle Cliff ridge by the Lafayette road, to Echo lake, 

 there is a mixture of hard gneisses, with a feldspathic breccia dipping 

 underneath the porphyritic gneiss. As the breccia is largely composed 

 of porphyritic fragments, it must be of more recent origin than the other 

 rocks, although occupying an inferior position. Our conclusion is, that 

 there is an overturn along this ridge, and a fault at its eastern extremity. 

 That will allow the existence of the anticlinal described heretofore and 

 figured on Plate VI, Fig. 7, and will explain the position of a newer be- 

 neath the older formation. 



At the base of Eagle cliff is a good place to procure specimens of the 

 rocks that have fallen down from above. Opposite the Profile I saw 

 fragments of porphyritic gneiss in the paste twenty inches long. Certain 

 specimens ringing sharply under the hammer exhibit crystals of quartz 

 in the feldspathic paste. A dyke of trap two feet wide, a little to the 

 east, dips 75° S. 78° W. There are only a few outcrops of this forma- 

 tion between the Profile house and the Basin. At the latter locality there 

 is a trappean-looking rock east of the road connected with the breccia. 



This formation has not been seen beyond the Basin in connection with 

 any other area, though there is an opportunity for further explorations on 

 the east, above the porphyritic gneiss. Conway granite covers this rock 

 on the west along the outlet of Tamarack pond. On the height of land 

 between Mts. Profile and Kinsman the breccia is largely developed. Of 

 the three peaks along this line the most northern is of granite; the 

 others are composed of this breccia, whose component materials average 

 coarser than at any other locality now known. The middle peak is 

 gneissic ; the third, and the valley preceding it, abound with fragments 

 of porphyritic gneiss twenty inches square. 



A trip to Kinsman pond, back of Mt. Pemigewasset, shows the same 

 breccia, it being probably continuous from the peaks south of Mt. Profile. 

 The rock did not appear in place ; but the great size of the angular blocks 

 indicates the character of the underlying material. 



The last line of outcrops referable to this formation ajjpears upon Har- 

 vard brook in Lincoln, above Georgianna falls. Mr. Upham visited the 



